Photographic light-sensitive material

ABSTRACT

A LIGHT-SENSITIVE MATERIAL COMPRISING A SILVER HALIDE EMULSION LAYER CONTAINING AN IODONIUM COMPOUND CORRESPONDING TO ONE OF THE FOLLOWING FORMULAE:   (PHENYL)2-I(+) Y(-) . HGX2 AND   DIBENZIODOLIUM Y(-) . HGX2   WHEREIN Y- REPRESENTS AN ANION AND X REPRESENTS A HALOGEN ATOM HAVING AN ATOMIC NUMBER GREATER THAN 9 IS DESCRIBED. THE IODONIUM COMPOUND STABILIZES THE EMULSION AGAINST ANY INCREASE IN FOG WITHOUT SUBSTANTIAL DESENSITIZATION OF THE EMULSION.

United States Patent 3,554,758 PHOTOGRAPHIC LIGHT-SENSITIVE MATERIALJozef Frans Willems, Wilrijk, Robrecht Julius Thiers, Brasschaat,Belgium, assignors to Gevaert-Agfa N.V., Mortsel, Belgium, a company ofBelgium No Drawing. Filed Dec. 7, 1967, Ser. No. 688,659 Claimspriority, application Great Britain, Mar. 6, 1967, 10,373/ 67 Int. Cl.G03c N34 US. Cl. 96109 6 Claims ABSTRACT OF THE DISCLOSURE Alight-sensitive material comprising a silver halide emulsion layercontaining an iodonium compound corresponding to one of the followinggeneral formulae:

and

wherein Y" represents an anion and X represents a halogen atom having anatomic number greater than 9 is described. The iodonium compoundstabilizes the emulsion against any increase in fog without substantialdesensitization of the emulsion. t

This invention relates to improved light-sensitive silver halideemulsions.

Light-scnsitive silver halide emulsions are in general silver halideemulsions against spontaneous formation and growth of fog known aschemical fog during prolonged storage or storage at high temperaturesand humidities or during development to maximum contrast and speed.Indeed, the fog increases with the degree and temperature ofdevelopment, and, in constant development circumstances, with the timethe light-sensitive emulsion is stored and with the temperature and therelative humidity of the atmosphere wherein the emulsion is stored. Itis evident that a light-sensitive emulsion should be obtained which isas stable as possible at high temperature and highrelative humidity forinstance in view of its use in tropical countries.

It is known to protect light-sensitive silver halide emulsions againstthe growth of chemical fog during storage by addition of stabilizers ofthe triazolopyrimidine type (azaindolizines). Heterocyclic thioxo andmercapto compounds too have been proposed for this purpose but show thedisadvantage of impairing the sensitivity'and gradation. The samedisadvantageous influence on the sensitivity occurs with the knownmercury compounds such as simple inorganic mercury salts, additioncomplexes of mercury with amines, organic mercury salts and heterocyclicmercury compounds. Indeed, these com pounds, when used in theconcentration necessary for obtaining a suflicient antifogging action,have a considerable desensitizing efi'ect.

3,554,758 Patented Jan. 12, 1971 It is also known that emulsionsstabilised with compounds of the triazolopyrimidine type still show atendency to fog formation in extreme storage circumstances i.e. at veryhigh temperatures and humidities and in extreme developmentcircumstances e.g. rapid processing at elevated temperatures. Theaddition to these emulsions of the above known mercury compounds reducesthe fogging tendency but, as mentioned above, at the cost of a reductionof the sensitivity.

It has now been found that when incorporating in a light-sensitivematerial comprising a silver halide emulsion layer double salts ofmercury(II) compounds and iodonium compounds, corresponding to one ofthe following general formulae:

Y- represents an anion e.g. a halogen anion, a nitrate anion, abisulphate anion, etc., and

X represents a halogen atom, and wherein the aromatic nuclei of saidcompounds include the substituted derivatives thereof e.g. substitutedwith an alkyl radical, a halogen atom, an alkoxy radical, a cyanoradical, an acyl radical or an acylamino radical.

The compounds of use according to the present invention can be preparedby reaction of the iodonium compound with the mercury(II) halide as isillustrated by the following preparations.

PREPARATION I: COMPOUND 1 A 31.6 g. (0.1 mole) of diphenyl iodoniumchloride are dissolved in 300 ml. of methanol by refluxing. To the andwherein:

boiling solution is added dropwise a solution of 27.1 g. (0.1 mole) ofmercury(II) chloride in 100 ml. of methanol. A precipitate formsimmediately. After the addition of the mercury(II) chloride solutionrefluxing of the mixture is continued for 1 hour. The precipitate formeddoes not dissolve anymore. Then the suspension is cooled and the solidproduct is filtered by suction and washed with ether. The yield beforerecrystallization is 57.5 g. The crude product is recrystallized fromdimethylformamide/ ethanol (6:4). Yield: 38 g. Melting point: 208-210 C.

PREPARATION II: COMPOUND 3 15.8 g. (0.05 mole) of diphenyl iodoniumchloride are dissolved in 150 ml. of methanol by refluxing. To theboiling solution is added dropwise a solution of 18 g. (0.05 mole) ofmercury(II) bromide in 200 ml. of methanol. A white precipitate formsimmediately. After the addition of the mercury(II) bromide solutionrefluxing is continued for 4 hours. The precipitate formed does notdissolve anymore. Then the suspension is cooled and the solid product isfiltered by suction and washed with ether. The yield beforerecrystallization is 32 g. The crude product is recrystallized fromdimethylformamide/methanol (3:7). Yield: 26 g. Melting point: 155 C.

As compared with the known mercury compounds used as stabilizers themercury(II) compounds according to the present invention when used inthe appropriate concentration do not cause or only to a slight extent adecrease in sensitivity.

The antifoggants according to the present invention are particularlysuitable for use in combination with compounds which sensitize theemulsion by development acceleration for example compounds of thepolyoxyalkylene type such as alkylene oxide condensation products asdescribed among others in United States Pats. 2,531,832 and 2,533,990,in United Kingdom Pats. 920,637, 940,051, 945,340 and 991,608 and inBelgian Pat. 648,710 and onium derivatives of amino-N-oxides.

The stabilizers according to the inventions can also be used incombination with other known stabilizer for instance with heterocyclicnitrogen containing thioxo compounds such as benzothiazoline-Z-thioneand 1-phenyl-2- tetrazoline-S-thione, with other mercury compounds, and,as said above, preferably with compounds of thehydroxytriazolopyrimidine type (azaindolizines).

The stabilizers according to the present invention may be incorporatedinto any type of light-sensitive material comprising a silver halideemulsion layer e.g. a spectrally sensitized or non-sensitized emulsionlayer, an X-ray emulsion layer or an emulsion layer sensitive toinfrared radiation. They may be incorporated into high-speed negativematerials as well as into rather low speed positive materials. Varioussilver salts may be used as light-sensitive salt e.g. silver bromide,silver iodide, silver chloride, or mixed silver halides e.g. silverchloro-bromide or silver bromo-iodide.

The silver halides are dispersed in the common hydrophilic colloids suchas gelatin, casein, zein, polyvinyl alcohol, carboxymethylcellulose,alginic acid, etc., gelatin however, being favoured.

The stabilizing agents are generally incorporated into the silver halideemulsion layer of the light-sensitive material; they may be added to theemulsion during no matter what step of emulsion preparation; however,they are preferably added to the photographic emulsion after thechemical ripening and just before coating of the emulsion. The addendaaccording to the present invention are incorporated into thephotographic emulsions according to the methods well known in emulsionpreparation. For instance they can be added to the emulsion in the formof a solution or of a dispersion according to the methods applied forincorporating colour couplers in the emulsion.

Instead of incorporating the compounds of the invention into theemulsion layer they can also be incorporated into a water-permeablelayer e.g. a gelatin covering layer or an intermediate layer.

The amount of mercury(II) compound employed in the light-sensitivesilver halide material depends on the particular type of emulsion andthe desired effect and can vary within very wide limits. The optimumamount of mercury(II) compound to be added can be determined for eachparticular type of material in a very simple way by application of theusual tests. Usually said compounds are employed in a ratio of about 0.1mg. to about 30 mg. per mole of silver halide, preferably from 0.5 mg.to 10 mg. per mole of silver halide.

The light-sensitive emulsions may be chemically as well as opticallysensitized. They may be chemically sensitized by effecting the ripeningin the presence of small amounts of sulphur containing compounds such asallylthiocyanate, allyl thiourea, sodium thiosulphate, etc. Theemulsions may also be sensitized by means of reductors for instance tincompounds as described in our French patent specification 1,146,955 andin our Belgian patent specification 568,687, imino-amino methanesulphinic acid compounds as described in our British patentspecification 789,823 and small amounts of noble metal compounds such asof gold, platinum, palladium, iridium, ruthenium and rhodium.

Other addcnda such as hardening agents, wetting agents, plasticizers,colour couplers, developing agents and optical sensitizers can beincorporated into the emulsion in the usual way.

The following examples illustrate the present invention.

Example 1 A high sensitive gelatino silver bromoiodide emulsion (i4.5moles percent of iodide) is divided into four aliquot portions A, B, Cand D.

To emulsion portion B is added per mole of silver halide 0.6 l0millimole (1.5 mg.) of mercury(II) cyanide, to emulsion portion C 0.6 10millimole (3.5 mg.) of compound 1 and to emulsion portion D 0.6 10millimole (4.6 mg.) of compound 3. The four emulsions are then coated ona subbed cellulose triacetate support and dried whereupon the fourmaterials thus obtained are stored for 5 days in an atmosphere of 57 C.and 34% of relative humidity.

The stored materials as well as four identical freshly preparedmaterials are exposed and developed for 5 minutes at 20 C. in adeveloping bath with the following composition:

Water-800 ccs. p-Monomethylaminophenol sulphate-4.5 g. Sodium sulphite(anhydrous)-50 g. Hydroquinone--6 g.

Sodium carbonate (anhydrous)32 g. Potassium bromide2 g.

Water up to 1000 ccs.

After the treatment in a stop bath, rinsing and fixing of the materialsthe following sensitometrie results are obtained.

TABLE Freshly prepared materials Stored materials Relative RelativeGradaspeed Gradaspeed Material Fog tion (percent) Fog tion (percent) Thespeed is given in relative values (i.e. in percent) In respect of theabsolute speed of an emulsion to which no mercury(Il) compound wasadded.

conditioned in a moist atmosphere of about 100% of relative humidity.Thereupon the materials are packed in aluminium-laminated paper andstored for 1 week at 57 C.

5 The following sensitometric results are obtained.

TABLE Freshly prepared materials Fog produeed in Amount of stabilizerper Grada- Relative stored Material mole of silver halide Fog tion speedmaterials A None 0. 11 2. 32 100 0. 32 B 2.3 mg. of compound 1 0. 12 2.12 100 0. 14 C 2.6 mg. of compound 3. 0. 12 2. 05 103 0. 14

Example 2 We claim:

ing to the formula:

wherein x has a value of about 135 and 2 g. of saponin as coating aid,is divided into 3 aliquot portions.

To two of these emulsion portions is added an amount of stabilizeraccording to the present invention as listed in the table below.

The three emulsions are coated on both sides of a cellulose triacetatesupport, which has been provided on both sides with a subbing layer, insuch a way that per sq. m. an amount of silver halide equivalent to 36g. of silver nitrate (both sides taken together) is present.

The emulsion layers are then overcoated with a gelatin antistress layer.

The three materials, A, B and C obtained are then exposed to X-rays withan X-ray radiation source of 80 kv. and developed for 8 min. at 26 C. ina common X- ray developer having the following composition:

Water800 ccs. p-Monomethylaminophenol hemisulphate--4 g. Hydroquinone g.

Anhydrous sodium sulphite65 g.

Anhydrous sodium carbonate--45 g.

Potassium bromide-5 g.

Water up to 1000 ccs.

The results obtained are listed in the following table.

A gelatino silver bromoiodide emulsion as described in Example 2 isdivided into 3 aliquot portions.

To two of these emulsion portions is added an amount of mercury(II)compound as listed in the table below.

The three emulsions are then further treated as described in Example 2and the resulting materials are 1. A photographic light-sensitive silverhalide emulsion including at least one compound corresponding to one ofthe general formulae:

wherein Y- represents an anion and X represents a halogen atom having anatomic number greater than 9, said compound being present in an amountsufficient to stabilize said emulsion with regard to fogging.

2. A photographic emulsion according to claim 1, wherein Y represents ahalogen anion, a bisulphate anion or a nitrate anion.

3. Photographic material according to claim 1, whereand in said compoundis present in an amount of from 0.1

mg. to 30 mg. per mole of silver halide.

4. A photographic emulsion according to claim 1, wherein said emulsionadditionally includes a stabilizer of the hydroxy-triazolopyrimidinetype.

5. A photographic emulsion according to claim 1, wherein said emulsionadditionally includes a development accelerator of the polyoxyalkylenetype.

6. A photographic emulsion according to claim 1, wherein said emulsionis a gelatino silver halide emulsion.

References Cited UNITED STATES PATENTS WILLIAM D. MARTIN, PrimaryExaminer R. M. SPEER, Assistant Examiner US. Cl. X.R. 96l08 UNITEDSTATES PATENT OFFICE CERTIFICATE OF CORRECTION Patent No. 3, 554, 758Dated January 12, 1971 Inventor(s) JOZEF FRANS WILLEMS and ROBRECHTJULIUS THEIRE It is certified that error appears in the above-identifiedpatent and that said Letters Patent are hereby corrected as shown below:

Column 6, claim 1, second formula set forth as Y'. HgY should read Y'.HgX

claim 3, line 1, "Photographic material" should read A photographitemulsion Signed and sealed this 7th day of March 1972.

(SEAL) Attest:

ROBERT GOTTSCHALK EDWARD M.FLETCHER ,JR.

Commissioner of Patents Attesting Officer

